Moreover, certain at least of the branches of science should likewise be treated by masters in the art of presentment, so that the layman interested in science, no less than the layman interested in history, shall have on his shelves classics which can be read. Whether this wish be or be not capable of realization, it assuredly remains true that the great historian of the future must essentially represent the ideal striven after by the great historians of the past. The industrious collector of facts occupies an honourable, but not an exalted, position, and the scientific historian who produces books which are not literature must rest content with the honour, substantial, but not of the highest type, that belongs to him who gathers material which some time some great master shall arise to use. Yet, while freely conceding all that can be said of the masters of literature, we must insist upon the historian of mankind working in the scientific spirit, and using the treasure-houses of science. He who would fully treat of man must know at least something of biology, of the science that treats of living, breathing things; and especially of that science of evolution which is inseparably connected with the great name of Darwin. Of course there is no exact parallelism between the birth, growth, and death of species in the animal world, and the birth, growth, and death of societies in the world of man. Yet there is a certain parallelism. There are strange analogies; it may be that there are homologies. How far the resemblances between the two sets of phenomena are more than accidental, how far biology can be used as an aid in the interpretation of human history, we cannot at present say. The historian should never forget, what the highest type of scientific man is always teaching us to remember, that willingness to admit ignorance is a prime factor in developing wisdom out of knowledge. Wisdom is advanced by research which enables us to add to knowledge; and, moreover, the way for wisdom is made ready when men who record facts of vast but unknown import, if asked to explain their full significance, are willing frankly to answer that they do not know. The research which enables us to add to the sum of complete knowledge stands first; but second only stands the research which, while enabling us clearly to pose the problem, also requires us to say that with our present knowledge we can offer no complete solution. Let me illustrate what I mean by an instance or two taken from one of the most fascinating branches of world-history, the history of the higher forms of life, of mammalian life, on this globe.